Acrylic monomers and the preparation thereof



3,025,322 ACRYLIC MONOMERS AND THE PREPARATION THEREGF Edwin MarvinSmolin, Springdale, and Richard Dean Anderson, Greenwich, Conn.,assignors to American Cyanamid Company, New York, N.Y., a corporation ofMaine No Drawing. Filed Nov. 26, 1958, Ser. No. 776,403 8 Claims. (Cl.260533) This invention relates to a novel method for preparing acrylicacid. More particularly, the invention relates to an improvement innickel salt-catalyzed, liquid-phase reactions at elevated temperaturesand pressures of equivalent amounts of acetylene, carbon monoxide andWater. It has been the experience in reaction systems of this type thatthe catalysts heretofore employed occasioned a number of side reactionswhich resulted in lowering spacetime yields of acrylic acid product. Forexample, precipitates were formed and accumulated in the reaction systemcausing mechanical difficulties. Also, the metal ions of the catalystsheretofore employed were usurped by t ese side reactions, thus rapidlyremoving them from solution and causing the reaction rate to fall off.

According to the present invention, however, the difficultiesencountered in the prior art have been overcome to a very considerableextent, thus greatly enhancing the product yield and catalyst recovery.Pursuant to the instant discovery, equivalent amounts of acetylene,carbon monoxide and water are reacted in the liquid phase at elevatedtemperatures and pressures in the presence of a combination of catalystscorresponding to the formulae wherein n is a value from to 1; xrepresents a value from 0 to 20; X is a halogen atom, including bromine,chlorine and iodine; and A represents an alkyl group having 1 to 18carbon atoms, preferably C to C an alkylsubstituted alkyl group having 1to 18 carbon atoms, pref-,

erably C to C said alkyl substituent having 1 to 8 carbon atoms; anunsubstituted aryl group, such as mono- -;;nuclear and po-lynuclear arylgroups; an alkyl-substituted aryl group, said alkyl substituent havingfrom 1 to 18 carbon atoms, preferably C to C an alkyl-substituted arylgroup of the type just mentioned in which the alkyl substituent having 1to 18 carbon atoms is, in turn, substituted with a member selected fromthe group consisting of C to C alkyl groups, anaryl group, an aralkylgroup having 1 to 18 carbon atoms in the alkyl moiety,

copper para-toluene sulfonate, nickel decylbenzene sul-' fonate, copperdecylbenzene sulfonate, nickel Z-napthalene sulfonate, copperZ-naphthalene -su1fonate,- nickel dodecylbenzene sulfonate, copperdodecylbenz'ene sulfonate, nickel bis(2,2-ditolylbutane)sulfonate,copper bis(2,2 tolylbutane)sulfonate, nickel bis(2 ,2 diphenylbutane)sulfonate, copper bis(2,2-diphenylbutane)sulfonate, nickelbis(1,1-dixylyleth-ane)sulfonate, copper bis-(1,1-dixylethane)sulfonate, and the like, and mixtures thereof.

Among'the nickel halides-and copper halides contem- Uni ted StatesPatent 0 3,025,322 Patented Mar. 13, 1962 ice plated herein are nickelchloride, copper chloride, nickel bromide, copper bromide, nickeliodide, copper iodide, and mixtures thereof.

It has been found, pursuant to the present discovery and as indicated bythe above general formulae, that best results are achieved when themetal hydrocarbon sulfonate and the metal halide have different metalcations. For instance, when nickel para-toluene sulfonate is the metalsulfonate, a copper halide, such as copper bromide, is paired with it.Similarly, When copper para-toluene sulfonate is the metal sulfonate, anickel halide, such as nickel bromide, is used.

Generally, the catalysts are present in sufiicient quantity to providefrom 0.1 to 8.0 percent by weight nickel salt, preferably 0.2 to 5.0percent by weight, basis the total weight of the non-gaseous mixture.cient quantity of catalyst is generally present to provide from 0.02 to5.0 percent by weight copper salt, preferably from 0.5 to 1.0 percent byweight, basis the total weight of the non-gaseous reaction mixture.

By the expression non-gaseous reaction mixture used herein, thenon-gaseous components charged to the reactor, i.e., the solvent, waterand catalyst, are intended.

Very desirable results are obtained when the nickelcontaining catalystis present in a molar excess with respect to the copper catalyst,usually in the mole ratio range of 2:1 to 4:1; however, a range of 1:1to 6:1 is suitable.

In carrying out the reaction of acetylene, carbon monoxide and water inthe presence. of the catalyst combination contemplated herein, it isvery advantageous to use an excess by volume of an inertoxygen-containing organicsolvent which is inert to the reactants underthe reaction conditions and miscible with Water. In other words, thesolvents are not irreversibly changed by the presence of Water and arenot able to react with acetylene or carbon monoxide. The solvents,therefore, should not contain free hydroxy, mercapto, or carboxy groups,olefinic or acetylenic linkages, or primary or secondary amino groups.The boiling points of the solvents are preferably below that ofacrylic-acid.

Preferred solvents are cyclic 'ethers, such as tetrahydrofuran, dioxane,and saturated aliphatic ketones, such as acetone, methyl ethyl ketoneand diethyl ketone.

While a slight excess of the solvent with respect to the water employedis suitable for example, parts by volume of solvent for 40 parts byvolume of water, much greater excesses of the liquid organic solvent arepreferred. 'For instance, a volume ratio of solvent to water in therange'of about :25 to about :5 is desirable.

While an equimolar ratio of acetylene to carbon monoxide is generallyused, the instant invention contemplates the use of an excess of eitherof these reactants up to about molar percent or more. i The reactionscontemplated herein advantageously may be conducted attemperatures aslow as C. and as high as 220 C. Preferably, reaction temperatures in therange of about C. to about 205 C are employed. On the other hand,pressures 'as low as 300 pounds per square inch gauge and as high asabout 900 pounds per square inch gauge are suitable, yet pressures inthe range of about 450 pounds per square inch gauge to 840 pounds persquare inch gauge are preferred.

. The process of the instant invention may be conducted in a batch,semi-continuous and continuous manner.

The water component utilized in the instant discovery may be present inan equivalent amount, basis the acetylene and carbon monoxide reactants.More commonly, however, these gaseous components are used in excess overthe water. An excess of acetylene and/orcarbon monoxide over water of 10to 20 molar percent orv more, for example, is often desirable.

As is well known, the acrylic acid produced by the novel process of thepresent invention is avery desirable material of commerce. For example,its use in prosthetic surgery, electrical insulation, etc. is veryextensive. Consequently, preparation of this material by a suitableeconomical and trouble-free process'has been the object of research formany years. Peculianly enough, as indicated above, loss of catalyst hasbeen a source of great anxiety and heretofore a wholly satisfactorysolution to the problem has not been found.

The metal hydrocarbon sulfonate catalysts of the present invention maybe prepared as shown by the following typical process:

EXAMPLE A To 13.5 parts of para-toluene sulfonic acid dissolved in wateris added suflicient aqueous barium hydroxide solution to exactlyneutralize the acid. To the resulting solution 9.3 parts of NiSO -6H Odissolved in water is added. Barium sulfate precipitates and is removedby filtration, the filtrate being then dried by heating to a temperatureof about 100 C. on a steam bath for a period of about 16 hours. A yieldof 16.2 parts of the hydrated nickel salt of para-toluene sulfonic acid(90 percent by Weight of theory) is recovered, the salt having theformula EXAMPLE I 1 A solution containing 12 parts by weight of water,88 parts by weight of acetone, 0.4 part by weight of NiBr -BH O, 0.2part copper decylbenzene sulfonate and 0.15 part by weight ofhydroquinone inhibitor is continuously pumped into a suitable highpressure reactor at the rate of 19 milliliters .per minute andmaintained at about 720 pounds per square inch gauge throughout thereaction. Concurrently a mixture of equal volumes of carbon monoxide andacetylene is continuously fed to the reactor in approximatelystoichiometric amounts, basis the water charged. The reaction iscontinued for a period of 15 hours at a temperature of 190 C. to 195 C.andreactor residence time of 200 minutes, computed by dividing thereactor volume by the feed rate, both in equivalent units.

A- product solution containing 24.2 percent by weight acrylic acid isrecovered. The recovery of nickel catalyst in the eflluent streamamounts to 30.9 percent by 3 weight; similarly, .the recovery of coppercatalyst at the end of 15 hours is 51.5 percent by weight, basis thecopper catalyst charged.

EXAMPLE II A solutionv containing 12 parts of water, 88 parts ofacetone, 0.05 part of cupric bromide, 0.15 part of hydro- .quinoneinhibitor and 0.3 part by weight of nickel do- 1 .decylbenzene sulfonateis passed into a high-pressure continuous reactor at the rate of 16milliliters per minute, thus providing a residence time of 119 minutes,computed as described in Example I, supra. While heating the reactor to200 C., equal volumes of acetylene and carbon monoxide are introducedtherein at a rate sufiicient to provide a 20 mole percent carbonmonoxide excess over the water and a 20 mole percent acetylene excessover the carbon monoxide. The pressure on the reacting mixture ismaintained at 710 pounds per square inch gauge throughout the reaction.

After 280 minutes of operation, a sample of the product of reaction istaken, titrated, and analyzed to determine the double bond contentthereof. Analysis shows an acrylic acid content of 15.5 parts by weightof the product. Higher boiling tarry materials are present only to theextent of 0.8 part by weight of the product. Further analysis of theproduct solution shows the presence of 83.10 percent by weight of thenickel catalyst charged, which catalyst is still in soluble form.

Comparative data disclose that Examples I and II, when repeated usingsimilar amounts of CuBr and NiBr respectively, for the hydrocarbonsulfonates in the examples, show recovery of less than one-third of thecatalyst recovered in these examples.

EXAMPLE III One hundred and fifty parts of a solution consisting of 120parts of water, 880 parts of acetone, 1.5 parts of cupric bromide, 1part of hydroquinone inhibitor and 6 parts of nickel methane sulfonatetrihydrate is charged to a suitable stainless steel rocking autoclave.The autoclave is then evacuated with a water aspirator and purged withnitrogen 3 times. After charging the vessel with sufiicient acetylene toproduce a pressure of 50 pounds per square inch gauge, the vessel isheated to 200 C., and the pressure therein raised to 750 pounds persquare inch gauge by introducing equal amounts by volume of acetyleneand carbon monoxide. Rocking of the autoclave is then started and thepressure drop is observed. After 23 minutes the pressure drops to 560pounds per square inch gauge and the reaction mixture is immediatelyrepressed by the addition of equal amounts by volume of acetylene andcarbon monoxide to create a pressure of 750 pounds per square inchgauge. Twenty-one minutes later the pressure is down to 560 pounds persquare inch gauge. The autoclave is then cooled to ambient temperature(21 C. to 23 C.) and the prodtezt solution removed therefrom. Thissolution contains 4.2 percent by weight acrylic acid. Over 75 percent byweight of the catalyst charged is recovered in unchanged form.

EXAMPLE IV Example III is repeated with the exception that the nickelmethane sulfonate trihydrate catalyst is replaced by the nickel salt'ofxylene sulfonic acid (trihydrate). As in Example III the pressure on thesystem is raised to 750 pounds per square inch gauge. The repressuringcycles may be represented by the following table:

Table I Pressure Drops Repressurcd to Tune (minutes) to (pounds per(pounds per square inch square inch gauge) gauge) At the end of thisperiod the autoclave is cooled to ambient temperature (21 C. to 23 C.)and the product solution removed therefrom. This solution contains 4.5percent by weight acrylic acid and over 75 percent by weight of thecatalyst charged to the autoclave, the catalyst being substantially inunchanged form.

EXAMPLE V Table 11 Pressure Drops to (pounds per square inch gauge)Repressured to (pounds per square inch gauge) Time (minutes) At the endof this period the autoclave is cooled to ambient temperature (21 C. to23 C.) and the product solution removed therefrom. This solutioncontains 3.5 percent by weight acrylic acid and over 75 percent byweight of the catalyst charged to the autoclave, the catalyst beingsubstantially in unchanged form.

EXAMPLE VI Example III is repeated with the exception that the nickelmethane sulfonate trihydrate is replaced by the nickel salt of2-tolyl-2-(tolyl sulfonic acid) butane (SI-I 0). As in Example III thepressure on the system is raised to 750 pounds per square inch gauge.

In addition, the system is repressured several times, also as in ExampleIII, above, the autoclave is cooled to ambient temperature (21 C. to 23C.), and the product solution removed therefrom. A desirable yield ofacrylic acid is realized and over 75 percent by weight of the catalystcharged is recovered in substantially unchanged form.

EXAMPLE VII Example III is repeated with the exception that the nickelmethane sulfonate trihydrate catalyst is replaced by mixed nickeldodecyl sulfonates (C H hydrocarbon fraction having a boiling point of200 C.-214 C.) prepared in the manner shown in Example A, above, from acommercial mixture of the corresponding sulfonic acids. In addition, thesystem is represented several times, also as in Example III, above, theautoclave is cooled to ambient temperature (21 C. to 23 C.), and theproduct solution removed therefrom. A desirable yield of acrylic acid isrealized and over 75 percent by weight of the catalyst charged isrecovered in substantially unchanged form.

While the present invention has been described in detail as to specificembodiments thereof, it is not intended that these details constituteundue limitations upon the scope of the invention, excepting, of course,insofar as these limitations appear in the appended claims.

We claim:

1. In a process for preparing acrylic acid by the reaction of equivalentamounts of acetylene, carbon monoxide and water in the liquid phase atan elevated temperature and pressure in the presence of a catalyst, theimprovement of carrying out said reaction in the presence of acombination of catalysts corresponding to the formulae Nil-n Gun whereinn is a value from 0 to 1; x represents a value from 0 to 20; X is ahalogen atom selected from the group consisting of bromine, chlorine andiodine; and A represents a radical selected from the group consisting ofan alkyl group having 1 to 18 carbon atoms, said alkyl substituenthaving 1 to 8 carbon atoms; an unsubstituted aryl group selected fromthe group consisting of phenyl and naphthyl; an alkyl substituted arylgroup, said alkyl substituent having from 1 to 18 carbon atoms and saidaryl group being selected from the group consisting of phenyl andnaphthyl; and an aryl substituted alkyl group having 1 to 18 carbonatoms, said aryl substituent being selected from the group consisting ofphenyl, tolyl, xylyl and naphthyl.

2. The process of claim 1 wherein the catalyst combination is thehydrated nickel salts of methane sulfonic acid having less than about 6moles of combined water and a copper halide selected from the groupconsisting of copper chloride, copper bromide and copper iodide.

3. The process of claim 1 wherein the catalyst combination is thehydrated nickel salt of naphthalene-2-sulfonic acid having less thanabout 6 moles of combined water and a copper halide selected from thegroup consisting of copper chloride, copper bromide and copper iodide.

4. The process of claim 1 wherein the catalyst combination is thehydrated nickel salt of 2-tolyl-2-(tolyl sulfonic acid) butane havingless than about 6 moles of combined water and a copper halide selectedfrom the group consisting of copper chloride, copper bromide and copperiodide.

5. The process of claim 1 wherein the catalyst combination is thehydrated copper salt of decylbenzene sulfonic acid having less thanabout 6 moles of combined water and a nickel halide selected from thegroup consisting of nickel chloride, nickel bromide and nickel iodide.

6. The process of claim 1 wherein the catalyst combination is thehydrated nickel salt of xylene sulfonic acid having less than about 6moles of combined water and a copper halide selected from the groupconsisting of copper chloride, copper bromide and copper iodide.

7. The process of claim 1 wherein the catalysts are present insufi'icient amounts to provide from 0.1 to 8.0 percent by weight nickelsalt, basis the total Weight of the non-gaseous reaction mixture, andfrom 0.02 to 5 percent by weight copper salt, basis the total weight ofthe non-gaseous reaction mixture.

8. The process of claim 1 wherein the catalysts are present insufficient amounts to provide from 0.2 to 5.0 percent by weight nickelsalt, basis the total weight of the non-gaseous reaction mixture, andfrom 0.5 to 1.0 percent by weight copper salt, basis the total weight ofthe non-gaseous reaction mixture.

References Cited in the file of this patent UNITED STATES PATENTS2,806,040 Reppe et al. Sept. 10, 1957 FOREIGN PATENTS 750,538 GreatBritain June 20, 1956 805,641 Germany May 25, 1951 863,194 Germany Ian.15, 1953 OTHER REFERENCES Berkman et al.: Catalysis, p. 515 (1940).German application Serial No. B29,113, printed Dec. 27, 1956.

1. IN A PROCESS FOR PREPARING ACRYLLIC ACID BY THE REACTION OFEQUIVALENT AMOUNTS OF ACETYLENE, CARBON MONOXIDE AND WATER IN THE LIQUIDPHASE AT AN ELEVATED TEMPERTURE AND PRESSURE IN THE PRESENCE OF ACATALYST, THE IMPROVEMENT OF CARRYING OUT SAID REACTION IN THE PRESENCEOF A COMBINATION OF CATALYSTS CORESPONDING TO THE FORMULAE